To keep things simple we will use degrees celcius.
For 2 weeks before hibernation keep your tortoise's daytime temperature above 24 degrees.We want the tortoise to hibernate without any food in it's stomach so do not feed during this time.Bathe your tortoise daily in tepid water, this will stimulate the tortoise to 'go to the toilet' and help clear the gut of food.Once your tortoise does not defecate int the water any more the gut is clear.
Spend a further 1-2 weeks placing your tortoise in cooler locations i.e. switch off it's heating, then move it to cooler rooms around the house.Check the fridge that you have chosen to hibernate your tortoise in has a max/min thermometer.Hibernation should be between 2 and 10 degrees, the ideal temperature is 5 degrees.This is because the tortoise uses very little energy at this temperature, therefore producing little waste.
Weigh your tortoise and record it's weight.Place your tortoise in a box just bigger than its self and put in some shredded paper.Put the small box into larger box and surround it with shredded paper, place the whole thing into the fridge that you have already established keeps its temperature to 5 degrees.Insulating the boxes will reduce the impact of any temporary temperature fluctuation, but remember it will not prevent freezing if the temperature drops bellow freezing at any time.

Throughout the hibernation period always regularly check the temperature within your fridge. Remember, we are aiming for 5 degrees.Check the weight of your tortoise weekly. Only allow 1% of your tortoise's initial weight to be lost per month. For example, on a 500 gram tortoise allow 5 grams to be lost each month.If your tortoise is losing too much weight bring out of hibernation immediately.Hibernate a two year old tortoise for one month, a three year old for two months and anything else for three months only. Do not ever hibernate your tortoise for longer than three months.
If your tortoise urinates whist in hibernation, warm it up straight away and seek veterinary advise.

Remove your tortoise from the fridge
Allow to slowly come up to room temperature during the day before returning to their heated vivarium.Your tortoise will now happily bask at over 24 degrees.You should offer some tortoise food and fresh green vegetables now as your tortoise should be hungry.
Bath in tepid water every day to ensure your tortoise is well hydrated.
If your tortoise is not drinking or eating within the first week, contact a vetinary advice immediately.